function s1_goto_dir(){
    cd "$1" || exit
}
function s2_touch_empty_file_with_given_name(){
    touch "$1"
}
function s3_make_directories(){
    mkdir -p projects/git/backup
}
function s4_create_6_files_in_projects(){
    touch projects/{linux1_centos,linux1_c_programming,linux2_centos,linux2_c_programming}_redhat
}
function s5_make_subdirectories(){
    mkdir projects/git/{linux1,linux2}
}
function s6_mv_files_to_subdirectories(){
    for file in projects/*_redhat; do
        dir="${file%%_*}"
        mv"$file""projects/git/${dir}"
    done
}
function s7_tar_and_backup_git_function(){
    tar -czvf projects/backup/git.tar.gz -C projects/git .
}
function s8_rm_git_function(){
    rm -rf projects/git
}
function s9_untar_and_restore_function(){
    tar -zxvf projects/backup/git.tar.gz -C projects
}
function s10_tar_and_backup_bz2_function(){
    tar -jcvf projects/backup/git.tar.bz2 -C projects/git .
}
function s11_find_out_sort_files_function(){
    find . -name "projects" -prune -o -type f -print | sort
}
function s12_dispaly_future_date_function(){
    date -d "+$(($1 * 15) minutes)" +%Y-%m-%d_%H:%M:%S
}
